Cases Spread but Hopeful Signs Emerge

ENLARGE

A child poses for the media after arriving at Britain's Gatwick Airport wearing a facemask.
Reuters

By

Betsy McKay

Updated May 2, 2009 12:01 a.m. ET

A new strain of flu is spreading quickly enough that it could cause a global pandemic soon, but there are signs a pandemic could be a mild one, officials at the Centers for Disease Control and Prevention said Friday.

Battening Down

Hong Kong quarantines, Mexico shuts off services, more.

Associated Press

A growing number of cases in Spain, New Zealand and other countries -- where travelers brought the disease home and could be spreading it to others -- means that sustained transmission of the disease is likely to take hold soon in more countries, Scott Dowell, head of the CDC's swine flu international team, said in an interview Friday. That development -- community outbreaks in more than one region of the world -- would fit the World Health Organization's criteria for its highest global alert level, phase 6.

"It's going to happen imminently," he said. A WHO spokesman said the agency is monitoring developments.

Signs of the epidemic's rapid spread were reported Friday from Colorado to Hong Kong. The CDC said 141 people in 19 U.S. states have been confirmed by laboratory tests to have or have had the strain, and more are emerging. Florida reported its first two cases -- an 11-year-old boy and a 17-year-old girl -- Friday afternoon. The U.S. Department of Education said 433 schools had been closed with 245,449 students dismissed in 17 states.

Flu: Complete Coverage

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Timeline

A South Korean woman who spent a week in Mexico in late April became the first person in the country to be confirmed with a case of swine flu, the national health ministry said Saturday. The agency also said it cut its list of suspected cases from two people to one after determining that one person had a different kind of influenza.

A total of 367 laboratory-confirmed cases have been reported in 13 countries, including 34 in Canada, 13 in Spain and eight in the U.K., according to the WHO. Hong Kong, the epicenter of the SARS epidemic as well as eruptions of avian flu, reported its first case, a visitor from Mexico. Authorities ordered 300 guests at the visitor's hotel to be quarantined for a week and posted police at the entrance.

Most cases haven't been severe, like many of those initially reported in Mexico were. A new CDC report said evidence showed that transmission of the disease in Mexico is widespread and that "less severe illness is common." The new virus lacks genes that made the 1918 pandemic flu and the H5N1 avian viruses so deadly, said Nancy Cox, director of the CDC's influenza division. The 1918 pandemic killed millions of people, while the H5N1 strain of avian flu has killed 257 people world-wide since 2003.

"We do not see the markers for virulence that were seen in the 1918 virus," she said at a news briefing.

ENLARGE

She cautioned, however, that scientists don't fully understand what makes flu viruses virulent. "There is a great deal that we do not understand about the virulence of the 1918 virus or other influenza viruses" that have caused severe disease, she said.

About one of every four people in the U.S. exposed to the new A/H1N1 virus develops respiratory illness, according to preliminary studies, Dr. Cox said in an interview, calling the rate "a little bit higher than seasonal flu." Between 5% and 20% of those exposed to seasonal flu strains become ill, she said. The wide variation is due to age differences: The low range applies to the adult population, while the rate is "much higher" among children in schools, she said.

President Barack Obama said Friday that the new swine flu might not turn out to be worse than seasonal flu, but that the government isn't taking any chances.

Mexican health authorities first alerted the CDC to a large number of patients they were seeing with severe respiratory disease April 12, Dr. Dowell said.

On April 14 and 17, the agency identified its first two cases of the new strain in the U.S., and wondered if there could be a link to the outbreak in Mexico. Dr. Dowell sent a note April 20 to an analyst asking him to closely monitor Mexican developments. "I said we've really got to track these diseases in Mexico," he said.

The CDC confirmed its fears of a swine-flu outbreak in Mexico April 23, when it tested virus samples received from authorities there, he said.

Tracking the Spread

Key developments on new flu outbreaks, according to CDC, WHO and government officials:

Deaths: 15 confirmed in Mexico and one confirmed in U.S., a toddler from Mexico who died in Texas.

Confirmed sickened world-wide, 562: 343 in Mexico; 149 in U.S.; 35 in Canada; 13 in Spain; 10 in Britain; four each in Germany and New Zealand; two in Israel; one each in Switzerland, Austria, China, Denmark and the Netherlands. Mexico is no longer releasing "suspected" numbers; the number of suspected cases was 2,498 before the tally was halted.

U.S. confirmed sickened, by state: 50 in New York; 28 in Texas; 18 in California; 16 in South Carolina; five in New Jersey; four each in Arizona and Delaware; three each in Indiana and Illinois; two each in Kansas, Colorado, Virginia, Michigan and Massachusetts; and one each in Ohio, Kentucky, Minnesota, Nebraska and Nevada.

Timeline of a Pandemic

On Wednesday, World Health Organization officials raised the alert level for A/H1N1 to phase 5, one step short of a full pandemic, as the disease continued to spread around the globe. See how the disease has spread, plus see the key for pandemic phases.

Phase 3 -- Through April 26, 2009

March 28, 2009: The first two known human cases of infection with the new flu strain are in the U.S. in late March, according to a report from the U.S. Centers for Disease Control and Prevention. A 9-year-old girl from Imperial County, Calif., reports symptoms on March 28, and a 10-year-old boy from San Diego County reports symptoms on March 30.

April 24: The U.S. reports seven confirmed human cases of the new flu strain. The government of Mexico reports an influenza-like illness in Mexico City; San Luis Potosi, in central Mexico; and Mexicali, near the U.S. border. Of the Mexican cases, 18 are confirmed as A/H1N1; 12 of those are genetically identical to the viruses from California. (See the WHO report.)

April 26: The U.S. reports 20 laboratory-confirmed human cases of swine influenza. Mexico reports 18 laboratory-confirmed cases and suspected cases in 19 of the country's 32 states. (See the WHO report.)

Phase 4 -- April 27 to April 29

April 27: Mexico reports 26 confirmed human cases of infection with the same virus, including seven deaths. The U.S. reports 40 confirmed human cases; Canada, six cases; and Spain, one case -- all with no deaths. (See the WHO report.)

April 28: Countries reporting laboratory-confirmed cases with no deaths are: the U.S. (64), Canada (6), New Zealand (3), the U.K. (2), Israel (2) and Spain (2). (See the WHO report.)

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